/** 
  * @author mr.doob / http://mrdoob.com/ 
  * based on http://papervision3d.googlecode.com/svn/trunk/as3/trunk/src/org/papervision3d/objects/primitives/Plane.as 
  */ 
  
 var Plane = function ( width, height, segments_width, segments_height ) { 
  
         THREE.Geometry.call( this ); 
  
         var ix, iy, 
         width_half = width / 2, 
         height_half = height / 2, 
         gridX = segments_width || 1, 
         gridY = segments_height || 1, 
         gridX1 = gridX + 1, 
         gridY1 = gridY + 1, 
         segment_width = width / gridX, 
         segment_height = height / gridY; 
  
  
         for( iy = 0; iy < gridY1; iy++ ) { 
  
                 for( ix = 0; ix < gridX1; ix++ ) { 
  
                         var x = ix * segment_width - width_half; 
                         var y = iy * segment_height - height_half; 
  
                         this.vertices.push( new THREE.Vertex( new THREE.Vector3( x, - y, 0 ) ) ); 
  
                 } 
  
         } 
  
         for( iy = 0; iy < gridY; iy++ ) { 
  
                 for( ix = 0; ix < gridX; ix++ ) { 
  
                         var a = ix + gridX1 * iy; 
                         var b = ix + gridX1 * ( iy + 1 ); 
                         var c = ( ix + 1 ) + gridX1 * ( iy + 1 ); 
                         var d = ( ix + 1 ) + gridX1 * iy; 
  
                         this.faces.push( new THREE.Face4( a, b, c, d ) ); 
                         this.uvs.push( [ 
                                                 new THREE.UV( ix / gridX, iy / gridY ), 
                                                 new THREE.UV( ix / gridX, ( iy + 1 ) / gridY ), 
                                                 new THREE.UV( ( ix + 1 ) / gridX, ( iy + 1 ) / gridY ), 
                                                 new THREE.UV( ( ix + 1 ) / gridX, iy / gridY ) 
                                         ] ); 
  
                 } 
  
         } 
  
         this.computeNormals(); 
  
 } 
  
 Plane.prototype = new THREE.Geometry(); 
 Plane.prototype.constructor = Plane; 
   
